The present invention relates to a method and apparatus for quenching heat treated objects, and, more particularly, to an improved quench chute for conveying objects from a furnace into a tank of quenching fluid.
Numerous objects, including nuts, bolts, bearings and other small parts, are subjected to heat treating processes in order to obtain certain physical properties. Typically, the objects are heated to a desired temperature (or cycled through a series of desired temperatures) while being exposed to a predetermined atmosphere. The parts are then typically subjected to a rapid cooling process, usually by submerging the parts in a quenching fluid such as water, oil or hot salt.
In practice, parts are typically loaded onto a conveyor passing through a furnace. As the parts travel through the furnace, they are heated to the desired temperature, or cycled through several temperatures. At the end of the furnace, the parts fall from the conveyor through a chute and into a tank of quenching fluid. At the bottom of the chute, the parts fall onto another conveyor, which removes them from the tank of quenching fluid.
Although the foregoing method has been found suitable for cooling heat treated parts, it has also been found that the parts may be damaged in the process. Specifically, many parts are still red hot and in a ductile condition as they fall through the quenching fluid, and may remain red hot even after they reach the top of the removal conveyor. These ductile parts may pile up at the bottom of the chute and be repeatedly struck by other falling parts. If this occurs, nicks, flattening of surfaces and mashing of threads on bolts or similar items, can occur. Such damage can result in numerous problems when the parts are shipped to an end user for use on a production line. This is particularly true if the parts will be fed into an automated assembly system via a magazine.
To compensate for the foregoing problem, several quench chutes have been produced with a series of angled baffles disposed therein. In practice, the parts strike the first baffle and are directed to the next one. This repeated striking of baffles slows the parts before they reach the bottom of the chute and strike other parts. However, it has been found that as much damage can occur from the parts striking the angled baffles as from the parts merely falling on each other. Additionally, the system of baffles does not prevent the parts from ultimately landing one on top of the other at the bottom of the chute. Furthermore, parts may become lodged on the baffles and not be dislodged until a different type of part is processed, thus resulting in mixing of parts.
Accordingly, it is an object of the present invention to provide an improved system for quenching heat treated objects.
Another object of the present invention is the provision of a system for quenching heat treated objects which will prevent damage from occurring to the objects.
Yet another object of the present invention is the provision of a system for quenching heat treated objects that prevents objects from becoming mixed with dissimilar objects in a tank of quenching fluid.
These and other objects of the present invention are attained by the provision of an improved apparatus for cooling heat treated objects. The apparatus includes a tank for holding quenching fluid, removal means for directing the objects to be cooled into the fluid, means for removing the objects from the fluid and means for directing the objects onto the removal means at an angle substantially parallel to an object-conveying surface of the removal means. The means for directing the objects into the fluid includes a chute having a curved portion that terminates in an end substantially parallel to an object-conveying surface of the removal means. The curved portion is positioned such that the objects glance off of the curved portion as they fall through the fluid. The apparatus further includes fluid manifolds having outlets that direct fluid into the chute along the length and width of the curved portion. The fluid directed into the chute decelerates the objects as they glance off of the curved portion. One dimension of the chute is constant along the entire length thereof. The removal means includes a conveyor disposed within the tank. A screen is disposed over the removal conveyor to prevent the objects from being blown off of the surface of the conveyor by the force of the final cooling sprays.
Other objects, advantages and novel features of present invention will become apparent when considering the following detailed description of embodiments in conjunction with the accompanying drawings.